Avoiding unintentional withdrawal of access device from a vessel

ABSTRACT

The present invention relates to a method and a device for avoiding that any of at least one first or at least one second access device ( 20, 30 ) is unintentionally withdrawn from a vessel ( 11 ). According to the present invention this is achieved by inserting the first access device in a first direction in the vessel, inserting the second access device in a second direction in the vessel, the second direction being different from the first direction and interconnecting the first and the second access device by providing a fixed length of an interconnecting device ( 50 ).

FIELD OF THE INVENTION

[0001] The present invention relates to a method and a device foravoiding that any of at least one first or at least one second accessdevice is unintentionally withdrawn from a vessel.

BACKGROUND

[0002] There are several occasions when access devices, such as needlesor catheters or the like, are inserted into a patient. The purpose isoften to deliver a liquid to the patient. This liquid may be a salinesolution that helps restore the fluid balance of the patient, a glucosesolution or other nutritional supplements or a solution containing adrug that should be delivered continuously. It may then be important tomake sure that the needles are not unintentionally withdrawn from thepatient, especially if this state remains undetected.

[0003] Other cases when access devices are regularly inserted into apatient are in blood cleaning treatments such as hemodialysis,hemofiltration, hemodiafiltration or plasmafiltration. For people whohave lost all or most of their kidney function, it is necessary to findalternative ways of cleaning the blood. One option is to have a newkidney transplanted. Due to the limited availability of organs, theimmunological demands on matching between organ and recipient and anumber of other reasons, this possibility is only open to some patients.

[0004] One alternative to transplantation is dialysis, which has to beperformed at regular intervals, usually several times per week, andtakes a few hours each time. In dialysis the waste products in the bloodare transported across a membrane to a cleaning fluid. In hemodialysis,the most common form of dialysis, blood is removed from the patientsbody and pumped into an extracorporeal fluid circuit by means of a bloodpump. The extracorporeal fluid circuit includes an external device, adialyser. The dialyser contains a membrane where blood is flowing on oneside and a dialysis fluid is flowing on the other side whereby the bloodis purified by means of dialysis. The purified blood is then returned tothe body. The blood is usually removed from and returned to the body viaaccess devices in the form of hollow needles, which are preferablyinserted into a blood vessel in the lower part of one arm. However alsoother locations for insertion of the needles are possible. In order tofacilitate a frequent access to the blood vessel, and also to increasethe available flow of blood in that vessel, it is a common practice tocreate a so-called arterio-venous fistula. Connecting a suitable arterydirectly to a vein by a surgical procedure creates the fistula. Anotherpossibility is to surgically insert an artificial vessel, i.e. graft, inbetween an artery and a vein, which graft is then used for the insertionof the needles. Hereinafter the expression vessel will be used while itis understood that the expression vessel comprises blood vessel as wellas artificial vessel, graft, fistula and other types of vessels for usein the herein disclosed technical field.

[0005] In either case it is, thus, required to insert access devicesinto the vessel of the patient, each time a dialysis treatment is to beperformed. It is then of utmost importance that the access devices arenot unintentionally withdrawn during the treatment. If the arterialaccess device (the one where blood is removed from the patient) isunintentionally withdrawn without being detected, the blood already inthe extracorporeal fluid circuit may continue to be pumped by the bloodpump. If the venous access device (the one where the blood is returnedto the patient) is still in place the blood will then be returned fromthe extracorporeal fluid circuit to the patient. When all the blood hasbeen returned to the patient by means of the blood pump and if the bloodpump is still in operation, air will be pumped into the patient. Thiswould be potentially harmful to the patient and has to be prevented. If,on the other hand, the venous access device would be unintentionallywithdrawn without being noticed, all the blood that should have beenreturned to the patient will instead be lost to the surrounding area.This may be fatal to the patient already after a few minutes, and shouldtherefore be prevented. If both access devices are withdrawn at the sametime, no harmful situation will normally arise, although the bloodpresent in the extracorporeal circuit will be lost. However, if thissituation remains undetected for a long time, treatment time is lost.

[0006] To prevent unintentional withdrawal of access devices it isnormal practice in dialysis machines to measure the pressure in anexternal tubing, constituting the extracorporeal fluid circuit, upstreamof the venous access device. This pressure is usually measured in a dripchamber attached to the dialysis machine. The pressure is measured bymeans of a pressure sensor. For the detection of unintentionalwithdrawal of the venous access device from the vessel, any alarm mustbe connected to tightly limited intervals of acceptable changes of thevenous pressure. A problem with this technique is that the pressure atthe site of the pressure sensor is a result of static pressures due to aheight difference between the drip chamber where the pressure ismeasured and the tip of the access device where the pressure in thevessel is measured and the pressure drop due to the flow of blood in theexternal tubing. It may therefore happen that changes in the heightdifference of the venous access device and the changed flow resistancewhen the access device is withdrawn counteract each other so that theresulting pressure change is too limited to be detected, i.e. thechanges of the venous pressure is kept within the accepted interval. Anunintentionally withdrawn venous access device may lead to fatal resultsfor the patient.

[0007] There is, thus, a need for devices that may increase the safetyagainst unintentional withdrawal of any access device during dialysis,and a number of methods have been suggested. The suggested methods maybe divided in two different classes. One class of methods aims atdetecting when any access device is withdrawn in order to give an alarmto the user. The other class of methods aims at physically preventingthe withdrawal of any access device.

[0008] Detection of withdrawal of any access device may be made e.g. byuse of a reed-relay fixed to the skin which can detect the movement of amagnet mounted in the blood tube as suggested in U.S. Pat. No.5,578,003. Another possibility is to attach fluid sensing devices, e.g.based on measurement of electrical conductivity, on the skin around theaccess devices, which is suggested in the PCT application WO 99/24145.

[0009] These methods do not prevent the withdrawal of access devices,and manual intervention, as a result of the emission of an alarm signal,is therefore needed to avoid a fatal outcome.

[0010] Safer in this respect are the devices that aim at preventing thewithdrawal of the access devices. Such devices are e.g. disclosed inU.S. Pat. No. 3,900,026, U.S. Pat. No. 5,084,026, U.S. Pat. No.5,112,313 and U.S. Pat. No. 5,449,349. They all describe devices thatare attached to the patients skin, either by tape or by straps aroundthe arm, and to which a single access device may be secured. Fordialysis two such devices are needed, one for each access device. It istime consuming to secure each access device in this way.

[0011] An alternative solution is provided by the device described inU.S. Pat. No. 5,911,706, U.S. Pat. No. 5,954,691 and U.S. Pat. No.6,013,058 and in PCT applications WO 00/16834, WO 00/16844, WO 00/40282and WO 00/53245. This device is implanted surgically under the skin, andis brought in permanent connection with the vessel using two accessdevices, one for extracting blood and one for returning blood, which arealso in their entire length located within the patient's body. Each timethat a dialysis procedure is to be performed access is gained to thevessel by inserting two access devices in parallel through the skin ofthe patient and into specially designed ports in the implanted device.These ports are so designed as to close off the access to the vesselwhen no access devices are inserted. The device is further designed tolock the access devices in their position when they are inserted intothe device in order to prevent unintentional withdrawal of the accessdevices. As a further safety measure, both access devices are linkedtogether so that if one of the access devices would be unintentionallywithdrawn despite the locking mechanism, the other access device wouldalso be withdrawn. The device requires a surgical procedure for itsinsertion. Due to immunological and other mechanisms in the human body,such implanted devices have a very limited lifespan in the body. It istherefore a short-term solution for the blood access to dialysispatients. It is quite a costly device compared to the use of ordinarydialysis access devices.

[0012] WO 01/03754 discloses an insertion guide for inserting anarterial access device and a venous access device, respectively, into avessel in the form of a fistula. The insertion guide guides therespective access device into the fistula. The access devices aresecured in their inserted position by means of a latching piece, whichis connected to the respective access device and arranged in a recessedchannel and locked in position by means of a clamping screw. This deviceis limited with respect to how, e.g. in respect of choice of directions,access devices may be arranged in the fistula. This device iscomplicated from the point of view of avoiding unintentional withdrawalof any access device.

DISCLOSURE OF THE INVENTION

[0013] One object of the present invention is to provide a method and adevice for avoiding that any of at least one first or at least onesecond access device is unintentionally withdrawn from a vessel. Thepresent invention is provided by securing that the at least one of thefirst or the at least one of the second access devices is maintained inplace by means of the at least one other access device.

[0014] According to the present invention this is achieved by insertingthe at least one first access device in a first direction in a vessel ofthe patient, inserting the at least one second access device in a seconddirection in the vessel, the second direction being different from thefirst direction and interconnecting the at least one first and the atleast one second access device and providing a fixed length of aninterconnecting device. As stated above the expression vessel is hereindefined so as to comprise blood vessel as well as artificial vessel,graft, fistula and other types of vessels for use in the hereindisclosed technical field. What constitutes different first and seconddirections will be further discussed below. For hemodialysis treatmentsit is e.g. common practice to let the at least one first or the at leastone second access device be directed against the blood stream whereasthe other one is facing essentially the opposite direction. It is alsocommon practice to use access devices provided with so-called wings bymeans of which the access device is secured to the patient by means oftape or the like. In one embodiment of the present invention the atleast one first or the at least one second access device is providedwith an abutment. The abutment and the wings, respectively, allowinsertion of the respective access device a predetermined distance intothe vessel before the wing or the abutments prevents the access deviceto be further inserted. According to the invention the at least onefirst and the at least one second access device, respectively, isattached and secured to each end of an interconnecting device in such away that the interconnecting device is placed in between the accessdevices. This interconnection of the at least one first and the at leastone second access device has the effect that if for example the at leastone first access device by an external force is pulled in a directionout of the vessel, the force will be transferred by the attachedinterconnecting device to the at least one second access device. Due tothe chosen angle between the first and the second insertion direction ofthe respective access device this will force the at least one secondaccess device in the direction further into the vessel. However, onlyvery limited movement is possible in this direction, since the accessdevice is stopped both by internal resistance at the tip of the accessdevice and by the external design in the form of a wing or an abutmentarranged on the access device as discussed above. The unintentionalwithdrawal of any of the at least one first or the at least one secondaccess device is thereby avoided.

[0015] Sufficiently different first and second insertion directions areherein defined as non-parallel directions. If the first and the seconddirection is the same, or nearly the same, and the access devices areattached to each other, this will assure that it is impossible towithdraw one access device alone. Instead both access devices will inthat case be withdrawn together. This is not satisfactory, since all theblood present in the extracorporeal fluid circuit will then be lost. Anangle between the first and the second direction is thereforerecommended to be at least in the magnitude of 30° in order to avoiddirections, which are nearly the same. Preferably the angle between thefirst and the second insertion direction is at least in the magnitude of45° and most preferably in the magnitude of 180°. The expression “in themagnitude of” is herein used in order to take into account that tissuesurrounding the area where the respective access devices are inserted issomewhat resilient and that the distance the respective access device isinserted into the vessel may differ.

[0016] If the at least one first and the at least one second accessdevice is inserted in a first and a second direction, respectively,where the second direction is substantially opposite to the firstdirection, the connecting device will prevent any unintentionalwithdrawal of any of or both of the at least one first and the at leastone second access device. A substantially opposite direction comprisesinsertion directions where the tips of the respective access device arearranged facing each other. In an alternative embodiment the tips arearranged facing away from each other. A further possibility according tothe invention is to place the at least one first and the at least onesecond access device perpendicular to each other. Also other angles arepossible according to the invention as long as the withdrawal of the atleast one first and/or the at least one second access device wouldrequire adjustment, i.e. shortening or elongation (lengthening) of theinterconnecting device.

[0017] A rod like member may constitute the interconnecting device. Theinterconnecting device is in one embodiment of the invention designedwith a first and a second end each provided with an interlocking device.The interlocking device is optionally arranged on the at least one firstand the at least one second access device, respectively. In a furtherembodiment of the present invention the interlocking device is partlyarranged on the interconnecting device and partly on the at least onefirst and the at least one second access device, respectively, in theform of mating bodies. The interconnecting device is preferably lockedonto the respective at least one first and at least one second accessdevice at a position behind any wing or abutment (away from thepatient). In order to accommodate the different insertion directions atwhich the access devices may be inserted, the connection between theinterlocking devices at each end of the connecting device and theinterconnecting device is preferably made in the form of a ball joint orthe like that allows at least partly pivotal connection. This will allowthe interlocking device to be positioned in a variety of angles withrespect to the interconnecting device.

[0018] In an alternative embodiment of the present invention the accessdevices are designed so that part of the interlocking device ispermanently mounted on the access device during production of it. Thispermanent part of the access device may then include a ball shaped tip,which is designed to fit in a mating holder at the end of the connectingdevice. The access device is then connected to the interconnectingdevice by snapping the ball shaped tip into the mating holder of theinterconnecting device.

[0019] In another embodiment of the present invention the length of theinterconnecting device is made adjustable in order to accommodate allpossible distances between the access devices that may be desired fordifferent patients or at different occasions. This adjustable length maye.g. be accomplished by a telescopic design of the interconnectingdevice, whereby two or more parts may be moved more or less into or outof each other. In a further embodiment of the present invention thelength of the interconnecting device is made adjustable in a way thattwo or more parts are movable in relation to each other by sliding theparts over each other or in parallel to each other. When the desiredlength has been decided, the two or more parts of the interconnectingdevice are fixed or locked together or in relation to each other by oneor more locking mechanisms. The design of the locking mechanism may besuch as to allow the interconnecting device to assume any length betweenits minimum and maximum. The locking mechanism may alternatively bedesigned to allow the choice of one out of a limited number of lengths.

[0020] In one embodiment of the present invention the adjustable lengthof the interconnecting device in the form of a rod like member isaccomplished by splitting the rod like member into two or more separaterod like members that are placed in parallel, but at different positionsin the longitudinal direction so as to achieve the desired length.

[0021] These separate rod like members are then fixed together at two ormore positions. The surface of the rod like members may further beshaped in a saw tooth pattern along one side. Letting the saw toothpatterns of the different rod like members face each other will thenprevent any movement of the rod like members in relation to each otherafter fixation.

[0022] Further objects, features and advantages of the present inventionwill appear from the detailed description of the invention given belowwith reference to the drawings, which include different embodiments ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a schematic cross-sectional view of a first embodimentof the invention.

[0024]FIG. 2 is a partial view similar to FIG. 1 and shows a symbolicinterlocking device.

[0025]FIG. 3 is a partial plan view of the symbolic interlocking deviceof FIG. 2.

[0026]FIG. 4 is a partial plan view of a symbolic telescopic rodinterconnecting the access devices of FIG. 1.

[0027]FIG. 5 is a view similar to FIG. 1 with a different symbolicallyshown placement of the access devices.

[0028]FIG. 6 is a view similar to FIG. 1 with a still differentsymbolically shown placement of the access devices.

[0029]FIG. 7 is a view similar to FIG. 1 with yet another symbolicallyshown placement of the access devices.

[0030]FIG. 8 is a schematic plan view showing the angle between theaccess devices.

[0031]FIG. 9 is a partial view similar to FIG. 2, showing symbolicallyan alternative interlocking device.

[0032]FIG. 10 is a plan view of a symbolically shown rod lockingmechanism.

[0033]FIG. 11 is a plan view of a symbolically shown different rodlocking mechanism.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0034] One embodiment of the present invention will now be described indetail with reference to the figures. Referring to FIG. 1, a first and asecond access device in the form of a first and a second needle 20 and30 has been inserted through the skin 10 of a patient and into a vessel11. In the preferred embodiment of the invention the needles are madeout of a rigid material, e.g. stainless steel which is often used inmedical supplies, and their size may be in the range 14-17 gauge with alength of 20-30 mm as is usually used in hemodialysis. The two needletips 21 and 31 are facing substantially opposite directions. Each of theneedles is provided with a wing 22 and 32. Such wings are often presenton such needles. Each end of an interconnecting device in the form of astiff rod 50 is attached to the respective needle at a position behindthe wings 22 and 32, and is secured to the respective needle by means ofsymbolically shown interlocking devices 60 and 70. Also shown areflexible blood tubes 25 and 35 that lead the blood from the first needleto the not shown extracorporeal fluid circuit, and back again to thesecond needle.

[0035] One embodiment of the symbolically shown interlocking device 70,which corresponds to 60, is shown in FIG. 2. To a needle holder 80 isfixed a connecting rod 90, which ends in a ball 91. Together with amating ball holder 92 arranged on the interconnecting device the ball 91forms a ball joint, by which the needle holder 80 is connected to theinterconnecting device in the form of the rod 50 in such a way as toallow it to rotate or pivote freely or at least partly freely around theball 91.

[0036] The symbolically shown interlocking device 70 is shown from abovein FIG. 3 with the needle holder 80 in an open position ready to beplaced around the needle. The needle holder 80 consists of two halves 81and 82, each having arms designed to snap around the needle. The arms ofhalf 81 are designed to fit in between the arms of half 82 when theneedle holder is closed as indicated in FIG. 2. The arms are furtherdesigned in such a way as to allow them to snap together in order tostay in a closed position. The holder 80 is placed on the needle afterinsertion in the vessel, and may be placed at a suitable location alongthe needle above the wing 22, 32 and before the tube 25, 35. The needleis optionally provided with a pair of nipples (not shown) in betweenwhich the holder 80 is placed and secured from sliding along the needle.In this way, the rod 50, with a fixed length of the rod, may accommodatea certain distance span.

[0037] In another embodiment of the invention the length of theinterconnecting device is adjustable, in steps or continuously. FIG. 4shows in greater detail, however symbolically, one embodiment of aninterconnecting device in the form of a stiff rod 50 with adjustablelengths which is constructed from two rods 51 and 52 as follows. Rod 51is hollow, with its inner diameter slightly larger than the outerdiameter of rod 52. The length of rod 50 is telescopically adjusted bysliding rod 52 into rod 51 until the desired length of rod 50 isachieved. The rods 51 and 52 are secured to each other in this positionby tightening a screw 53 on to rod 51. The design of the screw 53 issuch that when it is screwed on to rod 51, this will force the end ofrod 51 firmly against rod 52 and thus lock it in place. The details ofthis construction is known per se.

[0038] A suggested use of the present invention will now be described.The two access devices in the form of needles to be secured fromunintentional withdrawal are first inserted into the vessel of thepatient as shown in FIG. 1, with the tips of the needles facing awayfrom each other, and the needles inserted in essentially oppositedirections. The screw 53 on the stiff rod 50 in FIG. 4 is opened up sothat the two rods 51 and 52 are freely movable to allow the length ofstiff rod 50 to be adjusted. One end of the stiff rod 50 is thenattached to one of the needles by closing the needle holder halves 81and 82 around the needle at a position behind the needle wings 22, 32,as shown in FIG. 1 or behind any abutment 33. The two halves 81 and 82are snapped together so that they will stay in the locked position. Thelength of the stiff rod is then adjusted, but without tightening thescrew 53, so that the other end of the stiff rod 50 can be attached tothe second needle. This is done in exactly the same way as for the firstneedle. When both ends of the interconnecting device have been attachedto the respective needle, the needle positions in the vessel of thepatient are adjusted if necessary. Finally, the screw 53 is tightened sothat the two rods 51 and 52 are fixed to each other, and the length ofthe stiff rod 50 is fixed and is no longer unintentionally adjustable.To increase the safety even further, the stiff rod 50 may also be tapedto the skin of the patient.

[0039] The scope of the invention is by no means limited to theembodiment described above.

[0040] The access devices may e.g. be placed in other configurations.One alternative is shown in FIG. 5, where the access devices 20 and 30are still facing essentially opposite directions, but with the tips 21and 31 facing each other instead of away from each other as in FIG. 1.

[0041] Yet another possible configuration is shown in FIG. 6, where theaccess devices are crossed.

[0042] As appears from FIGS. 1, 5 and 6, the wings 22,32 are disposedclosely to the entrance point through the skin. These wings may befolded down and secured to the skin via tape or the like. Such a wing22, 32 may optionally be used for limiting the insertion distance of theaccess device it is related to. If one of the access devices tends to bepulled out due to an external force, the other access device will bepushed further into the skin, until any optional wing 22, 32 or optionalabutment 33 abut the skin and prevents further movement of the accessdevice in the insertion direction. Thus, the assembly of the at leastone first and the at least one second access device and theinterconnecting device may move slightly, but not sufficiently forwithdrawing one or more of the access devices. Moreover, frictionalforces counteract such movement.

[0043] In one embodiment of the present invention the interconnectingdevice is arranged as close as possible to the skin, since that wouldprevent unintentional movement. In a further embodiment of the presentinvention the interconnecting device is attached to the skin with aplaster or strap, in order to further increase safety.

[0044] In one embodiment of the present invention the at least one firstaccess device and the at least one second access device are arrangedwith an angle relative to each other as shown in FIG. 7, where the skinof the patient is shown from above. The access devices here in the formof needles 20 and 30 penetrate the skin through the openings 12 and 13made by the needles. Provided that the needles are inserted sufficientlydeep into the vessel of the patient tissue will prevent the needles frommoving sideways, and the interconnecting device 50 will preventaccidental removal of the needles, since this would require adjustmentof the length of the interconnecting device 50.

[0045]FIG. 8 defines an angle v between the two access devices in theform of needles 20 and 30. Small movements of the interlocking devices60 and 70 around the needles cannot be ruled out due to productiontolerances, the angle ν should therefore be greater than zero with somemargin. If the needles are produced in a material that is not completelyrigid, e.g. a plastic material, this margin needs to be increased.Furthermore, even if the needles are inserted with some depth, i.e. acertain distance into the patient, the tissue may to some extent giveaway to small sideways movements of the needles. This further increasesthe demand for a margin against small values of the angle v. It istherefore recommended that ν should be in the magnitude of at least 30degrees, preferably in the magnitude of 45 degrees, most preferablyabove the magnitude of 90 degrees.

[0046] In all of the configurations illustrated in FIG. 1 and in FIGS.5-8 the access devices in the form of two needles are symmetricallyarranged with respect to the surface, such as skin, through which theyare inserted. In an alternative embodiment the angles between each ofthe two needles and the normal to said surface are not equal. In such acase, each needle needs to form an angle with the normal of the surface.Such angle may be in the magnitude of more than 30 degrees and in mostcases it is preferred that the angle is in the magnitude of more than 45degrees, especially when the surface is somewhat flexible, as is thecase with the skin.

[0047] In all of the configurations illustrated in FIG. 1 and in FIGS.5-8 the two access devices in the form of needles have further beenassumed to reside within a common plane. It is then straightforward todefine the angle between the needles as done in FIG. 8. The needles mayalternatively be placed in a configuration that does not allow a commonplane to be defined wherein both needles are located. The requirement onthe needle configuration in such cases is still the same, namely thatthe withdrawal of one or both of the needles would require adjustment ofthe length of the connecting rod 50.

[0048] An alternative embodiment of the interlocking device 70 is shownin FIG. 9. When the access device in the form of a needle 20′ isproduced, the needle holder 80′ is permanently attached to the needle asan integral part of it. A connecting rod 90′ ending with a ball 91′ ispermanently attached to the needle holder 80′. The interconnectingdevice in the form of a stiff rod 50′ ends with a ball holder 92′designed to mate with the ball 91′. The stiff rod 50′ is connected tothe needle 20′ by snapping the ball 91′ into the ball holder 92′ so thata ball joint is formed.

[0049] In an alternative embodiment, not specifically shown butcorresponding to FIG. 9, the access device in the form of a needle 20′is produced in such a way that it is provided with a ball holder 92′.The interconnecting device in the form of a stiff rod 50′ is providedwith a ball 91′ permanently attached to its end. The ball holder 92′ isdesigned to mate with the ball 91′. The needle 20′ is connected to thestiff rod 50′ by snapping the ball 91′ into the ball holder 92′ so thata ball joint is formed.

[0050]FIG. 10 shows schematically an alternative way of making thelength of the interconnecting device in the form of a stiff rod 50adjustable by constructing it as two rods 51′ and 52′ each having a sawtooth pattern along one side. The two rods 51′ and 52′ are moved alongeach other, but at some distance from each other so that the saw toothpatterns 54 and 55 do not interact, until the correct length has beenachieved. By moving the two rods together, the saw tooth patterns willmate, and the length is fixed. The two rods are optionally kept in placeby two pins 56 and 58 that are inserted from above through both rods 51′and 52′ through mating holes in both rods. The lower ends of pins 56 and58 have hooks 57 and 59 that fold out when they pass out of the holes inrod 51′ and which make sure that the pins cannot be retracted again.

[0051] In an alternative embodiment of the present invention theinterconnection device includes a Velcro® fastening in a fashion similarto what is shown in FIG. 10 but for the locking pins 56, 58.

[0052] In the case of FIG. 1, the interconnecting device in the form ofa rod 50 may not shorten or decrease its length after application andfixation. In an alternative embodiment the rod may be arranged to beelongated or lengthened but be prevented from being shortened. The firstaccess device in the form of a needle is inserted. Then the secondaccess device also in the form of a needle is inserted, and at the sametime, the rod is elongated during the insertion. When the insertion isfinalized, the rod has been elongated as required. The mechanism is soarranged that the rod cannot be unintentionally shortened again. Thus, avery convenient double needle assembly is obtained. The arrangement maybe of a conventional nature, for example including two rods 51″ and 52″having teeth 65 and 66 permitting elongation but preventing shortening,as shown schematically in FIG. 11.

[0053] In the embodiment of FIG. 5, the opposite action should occur,namely that the interconnecting device in the form of a rod may not beunintentionally lengthened after insertion of the access devices in theform of a pair of needles.

[0054] The interconnecting device may be manufactured in plasticmaterial being sufficiently rigid for the intended operation, such as anacrylic material or PVC, which is often used for medical purposes.

[0055] As already indicated above there may be more than one firstand/or more than one second access devices that are interconnectedaccording to the invention. Thus, there may be arranged a hub, to whichseveral first and second access devices may be attached to form anaggregate of first and second access devices. At least one first and atleast one second access device need to be arranged according to thepresent invention.

[0056] The invention is intended to cover any pair of access devicespassing through a surface that may be interconnected according to theinvention. Thus, also catheters that are flexible may be interconnectedby means of the interconnecting device, provided that they are inserteddeeply into the vessel so that they cannot flex out of the holes 12, 13.

[0057] The invention has been described in connection with accessdevices for hemodialysis or similar treatment. However, every accesssituation where two access sites are required may benefit from thepresent invention. Thus, in the provision of nutritional solution ormedicaments, in which situation only a single access device normally isused, two access devices are sometimes required in case one of theaccess device may be occluded.

1. Method of avoiding unintentional withdrawal of any of at least onefirst or at least one second access device (20, 20′, 30) from a vessel(11), which comprises; inserting the at least one first access device ina first direction in the vessel; inserting the at least one secondaccess device in a second direction in the vessel, the second directionbeing different from the first direction; and interconnecting the atleast one first and the at least one second access device by providing afixed length of an interconnecting device (50, 50′, 51′, 51″, 52′, 52″).2. Method according to claim 1, characterized in adjusting the length ofthe interconnecting device (50, 50′, 51′, 51″, 52′, 52″) beforeintentionally withdrawing the at least one first or the at least onesecond access device (20, 20′, 30).
 3. Method according to claim 1,characterized in removing the interconnecting device (50, 50′, 51′, 51″,52′, 52″) before intentionally withdrawing any of the at least one firstor the at least one second access device (20, 20′, 30).
 4. Methodaccording to claim 1, 2 or 3 characterized in attaching theinterconnecting device (50, 50′, 51′, 51″, 52′, 52″) to the at least onefirst and the at least one second access device (20, 20′, 30),respectively, via an interlocking device (60, 70, 80, 80′, 81, 82, 90,90′, 91, 91′, 92, 92′).
 5. Method according to claim 1, 2, 3 or 4,characterized in inserting the at least one first or the at least onesecond access device (20, 20′, 30) a predetermined distance into thevessel (11).
 6. Method according to claim 4 or 5, characterized ininterconnecting the at least one first and the at least one secondaccess device by the interconnecting device (50, 50′, 51′, 51″, 52′,52″) before inserting.
 7. Method according to any of the precedingclaims, characterized in inserting the at least one first access devicein the first direction and inserting the at least one second accessdevice in the second direction where an angle between the first and thesecond direction is at least in the magnitude of 30°, preferably atleast in the magnitude of 45° and most preferably in the magnitude of180°.
 8. Device, which comprises at least one first and at least onesecond access device (20, 20′, 30), the at least one first access deviceto be inserted in a vessel pointing in a first direction and the atleast one second access device to be inserted in the vessel pointing ina second direction, the second direction being different from the firstdirection, characterized in that the at least one first and the at leastone second access device are to be interconnected by means of aninterconnecting device (50, 50′, 51′, 51″, 52′, 52″) having a length tobe fixed in such a way that unintentional withdrawal from the vessel ofany of the at least one first or the at least one second access deviceis avoided.
 9. Device according to claim 8, characterized in that theinterconnecting device (50, 50′, 51′, 51″, 52′, 52″) is attached to theat least one first and the at least one second access device (20, 20′,30), respectively, via an interlocking device (60, 70, 80, 80′, 81, 82,90, 90′, 91, 91′, 92, 92′).
 10. Device according to claim 9,characterized in that the interconnecting device (50, 50′, 51′, 51″,52′, 52″) by means of the interlocking device (60, 70, 80, 80′, 81, 82,90, 90′, 91, 91′, 92, 92′) is connected pivotally at the at least onefirst or the at least one second access device (20, 20′, 30).
 11. Deviceaccording to claim 8, 9 or 10, characterized in that a rod that is of afixed length constitutes the interconnecting device (50, 50′, 51′, 51″,52′, 52″).
 12. Device according to claim 8, 9 or 10, characterized inthat a rod that is of adjustable length constitutes the interconnectingdevice (50, 50′, 51′, 51″, 52′, 52″).
 13. Device according to claim 8, 9or 10, characterized in that a device comprising Velcro® constitutes theinterconnecting device (50, 50′, 51′, 51″, 52′, 52″).
 14. Deviceaccording to any of claims 9-13, characterized in that the interlockingdevice comprises a ball (91′) integrated with any of the at least onefirst or the at least one second access device (20, 20′, 30) and a ballholder (92′) integrated with the interconnecting device (50, 50′, 51′,51″, 52′, 52″).
 15. Device according to any of claims 9-13,characterized in that the interlocking device comprises a ball (91′)integrated with the interconnecting device (50, 50′, 51′, 51″, 52′, 52″)and a ball holder (92′) integrated with any of the at least one first orthe at least one second access device (20, 20′, 30)
 16. Device accordingto any of claims 8-15, characterized in that any of the at least onefirst or the at least one second access device (20, 20′, 30) is providedwith a device for abutment (22, 32, 33) limiting its insertion.
 16. Useof the device according to any of claims 8-16, in a process selectedfrom the group consisting of: hemodialysis, hemofiltration,hemodiafiltration, plasmapheresis, infusion of nutritional fluids,medication and fluid supplementation.